JP4774701B2 - Rolling bearing unit - Google Patents

Description

  The rolling bearing unit according to the present invention is used for, for example, rotatably supporting a wheel with respect to a suspension device of an automobile and measuring a load applied to the wheel.

  The wheels of the automobile are rotatably supported by the suspension system by a double row angular type rolling bearing unit. In order to ensure the running stability of automobiles, vehicle running stabilizers such as an antilock brake system (ABS), a traction control system (TCS), and a vehicle stability control system (VSC) are used. . In order to control such various vehicle running stabilizers, signals such as the rotational speed of the wheels and the acceleration in each direction applied to the vehicle body are required. In order to perform higher-level control, it may be preferable to know the magnitude of a load (one or both of a radial load and an axial load) applied to the rolling bearing unit via the wheel.

  2. Description of the Related Art Conventionally, devices described in, for example, Patent Documents 1 and 2 are known as devices for measuring a load related to a vehicle that can be used in such a case. Among them, Patent Document 1 describes a wheel bearing rolling bearing unit with a load measuring device that can measure a vertical load (radial load). As shown in FIG. 14, the rolling bearing unit with a load measuring device of the first example of this conventional structure supports a hub 2 for coupling and fixing wheels on the inner diameter side of an outer ring 1 supported by a suspension device. This hub 2 has a hub body having a rotation-side flange 3 for fixing a wheel at an outer end portion thereof (an end portion on the outer side in the width direction when assembled to a vehicle, the left end portion in FIGS. 14 to 17 and 19). 4 and the inner end portion of the hub body 4 (the end portion on the center side in the width direction in the assembled state in the vehicle, the right end portion in FIGS. 14 to 17 and 19) and are held down by the nut 5. And an inner ring 6. A plurality of rolling rings are provided between the double row outer ring raceways 7 and 7 formed on the inner peripheral surface of the outer ring 1 and the double row inner ring raceways 8 and 8 formed on the outer peripheral surface of the hub 2. The moving bodies 9a and 9b are arranged to freely rotate the hub 2 on the inner diameter side of the outer ring 1.

  A mounting hole 10 that diametrically penetrates the outer ring 1 is formed in a substantially vertical direction at an upper end portion of the outer ring 1 in a portion between the double row outer ring raceways 7 and 7 at an intermediate portion in the axial direction of the outer ring 1. Yes. In the mounting hole 10, a circular rod-shaped (round bar-shaped) displacement sensor 11, which is a load measuring sensor, is mounted. The displacement sensor 11 outputs a signal corresponding to the amount of change when the distance between the detection surface provided on the front end surface and the outer peripheral surface of the sensor ring 12 fitted and fixed to the hub body 4 changes. In the case of the conventional rolling bearing unit with a load measuring device configured as described above, the vertical load applied to the rolling bearing unit can be obtained based on the detection signal of the displacement sensor 11.

  In the conventional structure shown in FIG. 14, the rotational speed of the hub 2 can be detected in addition to the vertical load applied to the rolling bearing unit. For this purpose, the rotational speed detecting encoder 13 is fitted and fixed to the inner end of the inner ring 6, and the rotational speed detecting sensor 15 is supported on the cover 14 attached to the inner end opening of the outer ring 1. Yes. And the detection part of this rotational speed detection sensor 15 is made to oppose the to-be-detected part of the said encoder 13 for rotational speed detection through the measurement clearance gap.

  The rolling bearing unit with a load measuring device of the first example of the conventional structure as described above is for measuring the vertical load applied to the rolling bearing unit, but the lateral load (axial load) applied to the rolling bearing unit. The structure for measuring is also described in Patent Document 2 and the like and has been conventionally known. FIG. 15 shows a rolling bearing unit with a load measuring device described in Patent Document 2 for measuring a lateral load. In the case of the second example of this conventional structure, the rotation side flange 3a for supporting the wheel is fixed on the outer peripheral surface of the outer end portion of the hub 2a. A fixed-side flange 17 is fixed to the outer peripheral surface of the outer ring 1a for supporting and fixing the outer ring 1a to a knuckle 16 constituting a suspension device. A plurality of rolling rings are respectively provided between the double row outer ring raceways 7 and 7 formed on the inner peripheral surface of the outer ring 1a and the double row inner ring raceways 8 and 8 formed on the outer peripheral surface of the hub 2a. By providing the moving bodies 9a and 9b so as to be able to roll, the hub 2a is rotatably supported on the inner diameter side of the outer ring 1a.

  Further, a load sensor 20 is attached to a part surrounding the screw hole 19 for screwing the bolt 18 for connecting the fixed side flange 17 to the knuckle 16 at a plurality of positions on the inner side surface of the fixed side flange 17. Has been established. Each load sensor 20 is sandwiched between the outer side surface of the knuckle 16 and the inner side surface of the fixed-side flange 17 in a state where the outer ring 1 a is supported and fixed to the knuckle 16.

  In the case of the load measuring device for the rolling bearing unit of the second example having such a conventional structure, when a lateral load is applied between a wheel (not shown) and the knuckle 16, the outer surface of the knuckle 16 and the fixed flange 17 The inner surface strongly presses each load sensor 20 from both sides in the axial direction. Accordingly, the lateral load applied between the wheel and the knuckle 16 can be obtained by summing up the measured values of the load sensors 20. Although not shown, Patent Document 3 describes a method for obtaining the revolution speed of the rolling element from the vibration frequency of a member corresponding to the outer ring whose rigidity is partially reduced, and measuring the lateral load applied to the rolling bearing. Has been.

  Furthermore, as an invention for realizing a structure for accurately measuring a load applied to a rolling bearing unit at a low cost, there is an invention disclosed in Japanese Patent Application No. 2004-7655. The structure of this prior invention is based on the revolution speed of a pair of rolling elements (balls) constituting a rolling bearing unit which is a double-row angular ball bearing, and a vertical load or a lateral load applied to the rolling bearing unit. Measure. FIG. 16 shows a load measuring device for a rolling bearing unit according to the present invention. In the case of the structure according to the prior invention, the sensor unit 21 is inserted into the mounting hole 10a formed in the portion between the double-row outer ring raceways 7 and 7 at the intermediate portion in the axial direction of the outer ring 1, and the tip 22 of the sensor unit 21 is connected The outer ring 1 protrudes from the inner peripheral surface. The tip portion 22 is provided with a pair of revolution speed detection sensors 23a and 23b and one rotational speed detection sensor 15a.

  And the detection part of each revolution speed detection sensor 23a, 23b of these is provided in each retainer 24a, 24b which hold | maintained each rolling element 9a, 9b arrange | positioned in a double row freely, The revolution speed detection The revolving speed of each of the rolling elements 9a and 9b is made freely detectable by being closely opposed to the encoders 25a and 25b. In addition, the rotational speed of the hub 2 can be detected by making the detection portion of the rotational speed detection sensor 15a close to and opposed to the rotational speed detection encoder 13a that is externally fitted and fixed to the intermediate portion of the hub 2. According to the load measuring device for a rolling bearing unit according to the prior invention having such a configuration, a load (vertical load) applied between the outer ring 1 and the hub 2 regardless of fluctuations in the rotational speed of the hub 2. And lateral load).

That is, in the case of the load measuring device for a rolling bearing unit according to the above-described prior invention, an arithmetic unit (not shown) performs the outer ring 1 and the hub 2 based on the detection signals sent from the sensors 23a, 23b, 15a. One or both of the vertical load and the horizontal load applied between the two are calculated. For example, when calculating the load in the vertical direction, the computing unit calculates the sum of the revolution speeds of the rolling elements 9a, 9b in each row detected by the respective revolution speed detection sensors 23a, 23b. The vertical load is calculated based on the ratio to the rotational speed of the hub 2 detected by the speed detection sensor 15a. The lateral load is obtained by calculating the difference between the revolution speeds of the rolling elements 9a and 9b in the respective rows detected by the revolution speed detection sensors 23a and 23b, and the difference between the difference and the rotation speed detection sensor 15a. It calculates based on ratio with the rotation speed of the said hub 2 to do. This point will be described with reference to FIGS. In the following description, it is assumed that the contact angles α _a and α _b of the rolling elements 9a and 9b in each row are the same in a state where the lateral load Fy is not applied.

FIG. 17 schematically shows the rolling bearing unit for supporting the wheel shown in FIG. 16 and shows the action state of the load. Preloads F ₀ and F ₀ are applied to the rolling elements 9 a and 9 b arranged in a double row between the double row outer ring raceways 7 and 7 and the double row inner ring raceways 8 and 8. In use, the rolling bearing unit receives a vertical load Fz from the road surface as a reaction to the weight of the vehicle body. Further, a lateral load Fy is applied due to centrifugal force applied during turning. These preloads F ₀ , F ₀ , vertical load Fz, and lateral load Fy all affect the contact angles α (α _a , α _b ) of the rolling elements 9a, 9b. Then, the contact angle alpha _a, the alpha _b is changed, these rolling elements 9a, the revolution speed n _c of 9b changes. The diameter of the pitch circle of each of these rolling elements 9a, 9b is D, the diameter of each of these rolling elements 9a, 9b is d, the rotational speed of the hub 2 provided with each of the inner ring raceways 8, 8 is n _i , When the rotational speed of the outer race 1 provided with the outer ring raceway 7, 7 and n _o, the revolution speed n _c is expressed by the following equation (1).
n _c = {1− (d · cos α / D) · (n _i / 2)} + {1+ (d · cos α / D) · (n _o / 2)} (1)

As is clear from this equation (1), the rolling elements 9a, the revolution speed n _c of 9b, these rolling elements 9a, the contact angle α (α _a, α _b) of 9b varies in response to changes in As described above, the contact angles α _a and α _b change according to the vertical load Fz and the lateral load Fy. Thus the revolution speed n _c is changed according to these vertical load Fz and the lateral loads Fy. In this example, the hub 2 is rotated, since the outer ring 1 is not rotated, specifically, with respect to the vertical direction load Fz, the revolution speed n _c is slow enough to increase. Further, with respect to the lateral load Fy, as shown in FIG. 18, the revolution speed of the rolling elements 9a, 9a in the row supporting the lateral load Fy is increased (see the broken line a in FIG. 18). The revolution speed of the rolling elements 9b, 9b in the row not supporting Fy is slow (see the solid line B in FIG. 18). Accordingly, the rolling elements 9a of each row, based on the revolution speed n _c of 9b, will be determined the vertical load Fz and the lateral loads Fy.

However, the contact angle α which leads to a change in the revolution speed n _c, well above the vertical load Fz and the lateral load Fy changes while associated with each other, also varies the preload F _0, F ₀ To do. Also, the revolution speed n _c is changed in proportion to the rotational speed n _i of the hub 2. Therefore, these vertical load Fz, lateral loads Fy, preload F _0, F _0, to be considered in conjunction all the rotational speed n _i of the hub 2, it is impossible to correctly determine the revolution speed n _c . Of these, the preloads F ₀ and F ₀ do not change according to the operating state, so it is easy to eliminate the influence by initial setting or the like. The vertical load Fz contrast, lateral loads Fy, the rotational speed n _i of the hub 2, since the constantly changing depending on the operating conditions, it is impossible to eliminate the influence by the initial setting or the like.

In view of such circumstances, in the prior invention, as described above, when the vertical load Fz is obtained, the revolution speeds of the rolling elements 9a and 9b of the respective rows detected by the respective revolution speed detection sensors 23a and 23b. Is obtained, the influence of the lateral load Fy is reduced. Further, when obtaining the lateral load Fy, the influence of the vertical load Fz is reduced by obtaining the difference in revolution speed between the rolling elements 9a and 9b in each row. Further calculation, in any case, and the sum or difference, the rotational speed detecting sensor 15a is on the basis of the ratio between the rotational speed n _i of the hub 2 for detecting the vertical load Fz, or the lateral load Fy by and by eliminating the influence of the rotational speed n _i of the hub 2. Incidentally, the lateral loads Fy, when calculating on the basis of the ratio of the revolution speed of the rolling elements 9a, 9b of each column, the rotational speed n _i of the hub 2 is not necessarily required.

There are various other methods for calculating one or both of the vertical load Fz and the lateral load Fy based on the signals of the revolution speed detection sensors 23a and 23b. Such a method is described in detail in the above-mentioned Japanese Patent Application No. 2004-7655, and is not related to the gist of the present invention, so detailed description thereof is omitted. Further, as shown in FIG. 19, fitted to fix the rotational speed detection encoder 13b for obtaining the rotation speed n _i of the hub 2 to the inner end portion of the hub 2, the rotational speed detecting sensor 15b of the outer ring 1 It is also possible to support the cover 14a with the inner end opening closed.

  The above-described load measuring device for a rolling bearing unit according to the present invention can be manufactured at a relatively low cost compared to the structures described in Patent Documents 1 to 3 described above, and the vertical direction applied to the rolling bearing unit. The load Fz or the lateral load Fy can be accurately obtained. However, in order to obtain these loads Fz and Fy accurately and with high accuracy (with high resolution), the revolution speeds of the rolling elements 9a and 9b in the respective rows detected by the revolution speed detection sensors 23a and 23b are determined. It needs to be accurate and highly accurate. In order to obtain the revolution speed with high accuracy, the revolution speed detection encoders 25a and 25b are provided concentrically with the cages 24a and 24b in order to obtain the revolution speed as the rotational speed of the cages 24a and 24b. It is effective to increase the number of characteristic changes of the revolution speed detecting encoders 25a and 25b (to shorten the characteristic change pitch).

  Further, in order to accurately obtain the revolution speed, it is important to match the geometric center of each of the cages 24a and 24b with the rotation center (the revolution center of the rolling elements 9a and 9b in each row). On the other hand, in the detection signals of the respective revolution speed detection sensors 23a and 23b, an error in the magnetization pitch of the surface to be detected (pitch between the S pole and the N pole adjacent in the circumferential direction) occurs. The comparatively high frequency fluctuation | variation based on and the comparatively low frequency fluctuation | variation accompanying the whirling motion of the holder | retainer 24a, 24b have entered. If such fluctuations are not processed (reduced), the revolution speed of the rolling elements 9a and 9b in each row cannot be obtained accurately, and therefore the measurement accuracy of the vertical load and the horizontal load is deteriorated.

The reason why the above-described two types of fluctuations that lead to deterioration of the measurement accuracy of each load will be described with reference to FIGS. The inner surface of the pocket of the holder 24a (24b) holding the revolution speed detection encoder 25a (25b) (or having the function as the revolution speed detection encoder) and the surface of each rolling element 9a (9b) There is a gap between the (rolling surface) and the rolling elements 9a (9b) so as to be able to roll freely. Therefore, no matter how much the assembly accuracy of each component is increased, the center of the pitch circle of each of the rolling elements 9a (9b) (the center of rotation of the hub 2) O ₂ and the cage 24a ( There is a possibility that the rotation center O _{24 of} 24b) is shifted by δ as shown in an exaggerated manner in FIG. In the prior art, the direction of deviation by δ is not particularly restricted. Based on this deviation, the revolution speed detecting encoder 25a (25b) performs a swinging motion around the center O ₂ of the pitch circle.

  As a result of the swinging motion generated in this way, the detected surface of the revolution speed detecting encoder 25a (25b) has a moving speed in addition to the rotating direction. Then, the moving speed other than the rotational direction, for example, the lateral moving speed in FIG. 20 is added to or subtracted from the rotational speed. On the other hand, the revolution speed detection sensor 23a (23b) detects the revolution speed of each rolling element 9a (9b) based on the moving speed of the detected surface of the revolution speed detection encoder 25a (25b). The eccentricity of δ affects the detection signal of the revolution speed detection sensor 23a (23b) in which the detection surface faces the side surface of the revolution speed detection encoder 25a (25b).

  When the detection surface of the revolution speed detection sensor 23a (23b) is opposed to the side surface of the revolution speed detection encoder 25a (25b), the detection signal of the revolution speed detection sensor 23a (23b) is as shown in FIG. As shown by the chain line α in FIG. That is, even when the revolution speed of each rolling element 9a (9b) is constant, the revolution speed represented by the output signal of the revolution speed detection sensor 23a (23b) is sinusoidally as shown by the chain line α. Change. Specifically, when the moving speed in the left-right direction in FIG. 20 is added to the moving speed in the rotational direction, the output signal is a signal corresponding to a speed faster than the actual revolution speed. On the contrary, when the moving speed in the left-right direction in FIG. 20 is subtracted from the moving speed in the rotational direction, the output signal is a signal corresponding to a speed slower than the actual revolution speed. FIG. 20 shows the eccentricity δ exaggerated as compared with the actual case. For example, the vertical load Fz and the lateral load Fy applied to the rolling bearing unit are further increased in order to more strictly control for vehicle stability. In the case of obtaining accurately, it is necessary to eliminate the error due to the eccentricity.

  The pitch of the characteristic change on the side surface of the revolution speed detecting encoder 25a (25b) (for example, the pitch between the S pole and the N pole arranged on the side surface) should be essentially the same, but a manufacturing error (for example, Due to magnetization errors, etc., they may be slightly different from each other. Even based on this error, the detection signal of the revolution speed detection sensor 23a (23b) varies. The period of variation based on such an error in the magnetized pitch is much shorter (higher frequency) than the period of variation based on the above-mentioned whirling motion. For example, when the characteristic (repetition of S pole and N pole) of the side surface (detected surface) of the revolution speed detecting encoder 25a (25b) changes 60 times on the entire circumference of the detected surface, the magnetization is performed. The fluctuation period based on the pitch error is about 1/60 of the fluctuation period based on the swing motion.

  The detection signal output from the revolution speed detecting encoder 25a (25b) is as shown by a solid line β in FIG. 21 in which the above two types of fluctuations are added (superimposed). In order to accurately obtain the vertical load Fz and the lateral load Fy, it is necessary to reduce the two types of fluctuations. Among such variations, the relatively high frequency variation based on the manufacturing error such as the magnetization pitch is an electrical signal using an averaging filter, which has been widely known as a signal processing method. It can be easily reduced by processing.

  On the other hand, in order to prevent the deterioration of the accuracy of the revolution speed detection based on the relatively low frequency fluctuation accompanying the swinging motion, the revolution speed detection encoder is arranged at two positions on the opposite side in the radial direction. By adding the detection signals of the pair of revolution speed detection sensors, it is possible to eliminate the influence of the deviation between the two centers. However, in this case, two revolution speed detection sensors are required, which may increase the cost and installation space, and may be difficult to adopt.

  On the other hand, in the case of a general rolling bearing unit for a passenger car, each of the above-mentioned holdings can be achieved if a gap in the radial direction of the cage (pocket gap) between the rolling surface and the inner surface of the pocket is kept small. Even in a so-called rolling element guide structure in which positioning in the radial direction of the vessel is achieved by a rolling element, it is considered that the accuracy of the revolution speed can be suppressed to a practically satisfactory level. However, conventionally, there has been no technology that takes into account the suppression of the radial pocket gap as described above in terms of ensuring the measurement accuracy of the load applied to the rolling bearing unit.

  In addition, when the rolling bearing unit is used under the condition of supporting a large moment (torsional moment) in a direction in which the central axis of the outer ring 1 and the central axis of the hub 2 are displaced, the clearance is simply reduced with respect to all pockets. Then, one of the rolling elements strongly presses the inner surface of the pocket holding the rolling element based on the variation in the revolution speed of each rolling element, the difference in the trajectory of each rolling element, and the like. And the load which tries to deform | transform this retainer generate | occur | produces inside a retainer, and this retainer may be damaged. As another problem, sufficient grease cannot be applied to the rolling surface of each rolling element, resulting in a decrease in durability due to poor lubrication. For this reason, depending on the usage condition of the rolling bearing unit, it may not be preferable to reduce all pocket gaps.

  In view of such circumstances, Japanese Patent Application No. 2003-32148 discloses an invention that suppresses the whirling motion of the revolution speed detecting encoder with a structure as shown in FIGS. In the case of the structure shown in FIG. 22 among these, the weight 26 is made heavier than the other parts by fixing the weight 26 to a part in the circumferential direction of the cage 24a (24b). When the cage 24a (24b) rotates in accordance with the revolving motion of the rolling elements 9a, 9a (9b, 9b), the cage 24a (24b) has the portion provided with the weight 26 most radially outward. Sway around in a displaced state. Further, the assembly position of the revolution speed detecting encoder 25a (25b) with respect to the side surface of the rim portion 27 of the cage 24a (24b) is shifted by δ to the opposite side of the mounting position of the weight 26 by 180 degrees. . This δ corresponds to the amount of eccentricity δ shown in FIG. 20, and corresponds to the radial displacement of the cage 24a (24b) based on the gap between the inner surface of the pocket and the rolling surface. The size to be.

  In the case of the structure shown in FIG. 22 as described above, the swinging direction of the cage 24a (24b) is uniquely restricted, and the revolution speed detecting encoder 25a (25b) with respect to the cage 24a (24b) is controlled. The assembly position is shifted by the radial displacement of the cage 24a (24b) on the diametrically opposite side with respect to the swinging direction. Therefore, when the rolling elements 9a, 9a (9b, 9b) revolve, the rotational speed and the geometric center of the revolution speed detecting encoder 25a (25b) regardless of the swinging motion of the cage 24a (24b). Match. For this reason, it is possible to prevent a low-frequency fluctuation as shown by the chain line α in FIG. 21 from entering the detection signal of the revolution speed detection sensor 23a (23b). Even if the assembly position of the revolution speed detecting encoder 25a (25b) is not shifted (the encoders are supported concentrically with the respective cages), the weight 24 makes the cage 24a (24b) constant. It remains in a state of displacement in the direction and performs a stable swinging motion. Therefore, even if each encoder 25a (25b) is supported concentrically by each retainer 24a (24b), the revolution speed can be detected if a signal representing the revolution speed is appropriately calculated by an adaptive filter or notch filter. It is possible to remove (correct) low frequency fluctuations as indicated by the chain line α in FIG.

  Further, in the case of the structure shown in FIG. 23, the revolution speed detecting encoder 25a (25b) is supported and fixed to the cage 24a (24b) in a state where the geometric centers coincide with each other. Then, positioning of the cage 24a (24b) in the radial direction is performed by an inner ring guide in which a part of the inner circumferential surface of the cage 24a (24b) is brought close to and opposed to the outer circumferential surface of the hub 2. With this configuration, when the cage 24a (24b) rotates with the revolution motion of each rolling element 9a (9b), the cage 24a (24b) hardly swings and the revolution speed is reached. It is possible to prevent low-frequency fluctuations as shown by the chain line α in FIG. 21 from entering the detection signal of the detection sensor.

In the case of the structure shown in FIG. 22, in order to uniquely regulate the swinging direction of the retainer 24a (24b), the centrifugal force acting on the weight 26 is increased to some extent, and the retainer It is necessary to reliably displace 24a (24b) in the direction in which the weight 26 is installed. However, since the centrifugal force is proportional to the square of the rotational speed {revolution speed of each rolling element 9a (9b)}, the above weight is used in order to regulate the swinging direction of the cage 24a (24b) from low speed running. It is necessary to use a heavy component as 26. However, the heavy weight 26 is not preferable because it generates an excessive centrifugal force during high-speed traveling and may cause damage to the cage 24a (24b).
Further, in the case of the structure shown in FIG. 23, if the clearance between the inner peripheral surface of the cage 24a (24b) and the outer peripheral surface of the hub 2 is made too small, thermal expansion (shrinkage) due to temperature change occurs. Furthermore, there is a possibility that these two peripheral surfaces come into contact with each other (the gap is lost) and cannot be rotated normally. In particular, when the cage 24a (24b) is made of a material other than steel such as a synthetic resin such as a polyamide resin, the linear expansion coefficient is different from that of the hub 2 made of steel. It is difficult to set the gap small.

  In the above description, in order to accurately obtain the revolution speed of each rolling element, the necessity to suppress the swinging motion of the cage holding each rolling element has been described. However, it is always necessary to suppress the swinging motion of the cage from the aspect other than accurately obtaining the revolution speed of each rolling element. That is, even in the case of a general rolling bearing unit, the gap existing between the inner surface of each pocket provided in the cage and the surface of each rolling element is too large, and this cage is unstable due to the swinging motion. When a gentle movement is made, there is a problem that noise or vibration called so-called cage noise occurs. When such noise and vibration occur, the stress inside the cage increases, which not only leads to breakage of this cage, but also when the rolling bearing unit is incorporated in acoustic equipment, precision equipment, etc. Will degrade the performance of the device. Also from such a surface, it is necessary to suppress the whirling motion of the cage incorporated in the rolling bearing unit.

  As described above, if the gap between the inner surface of each pocket and the surface of each rolling element is reduced, the whirling motion can be suppressed, but the surface that ensures the measurement accuracy of the load applied to the rolling bearing unit. Therefore, conventionally, no particular consideration has been given to reducing the radial pocket gap as described above. Even if it is considered, if the gap is reduced with respect to all pockets and rolling elements, any of the rolling elements may change the inner surface of the pocket holding the rolling elements based on the variation in the revolution speed of each rolling element. A strong load is applied to the inside of the cage to cause deformation of the cage, which may cause the cage to break. In addition to taking in grease into the pockets and lubricating between the inner surfaces of the pockets and the surfaces of the rolling elements, the gaps collect grease and store the rolling surfaces and outer rings. Necessary for lubricating the rolling contact between the track and the inner ring track. Therefore, if the gap between the inner surface of each pocket and the surface of each rolling element is made small for all pockets, the lubrication state of the rolling bearing unit tends to be poor, which may not be preferable.

JP 2001-21577 A Japanese Patent Laid-Open No. 3-209016 Japanese Patent Publication No.62-3365

  The present invention has been invented to realize a rolling bearing unit that can reliably suppress the swinging motion of the cage holding each rolling element from the time of low-speed rotation in view of the circumstances as described above. Furthermore, if necessary, even when the rolling bearing unit is used under the condition of supporting a large moment in a direction in which the central axis of the outer ring equivalent member and the central axis of the inner ring equivalent member are displaced, the cage The invention was invented to make it possible to realize a structure that prevents excessive force from being applied and that can ensure lubricity.

The rolling bearing units of the present invention (the inventions according to claims 1 to 11 ) and the reference inventions related to the present invention (first to seventh reference inventions) are the same as conventionally known rolling bearing units. in the outer ring member having an outer ring raceway of the double row inner circumferential surface, and the inner ring member having an inner ring raceway of the double row outer peripheral surface, provided rollably between these outer ring raceways and both inner ring raceway A plurality of rolling elements, and a cage having a plurality of pockets for holding the rolling elements inside each of the rolling elements. The positioning of the cage in the radial direction is achieved by so-called rolling element guide based on the engagement between the inner surface of each pocket and the surface of each rolling element. And it is provided between the suspension apparatus and wheel of a motor vehicle, and is utilized in order to support this wheel rotatably with respect to this suspension apparatus.

In particular, in the rolling bearing unit according to the first reference invention, both amplitudes of the swinging motion in which the cage is displaced in the radial direction as the rolling motions of the rolling elements are included in a part of the cage. It is 1% or less of the pitch circle diameter (of the surface to be detected) of the revolution speed detecting encoder provided concentrically with the cage.
The second, fifth, and sixth reference inventions having a configuration that can be preferably adopted when implementing the first reference invention will be described later.
On the other hand, in the rolling bearing unit according to the third reference invention, the pocket clearance in the radial direction of the cage, which exists between the rolling surface of each rolling element and the inner surface of each pocket. The value is set to 1% or less of the pitch circle diameter (of the surface to be detected) of the revolution speed detecting encoder provided concentrically with the cage in a part of the cage.
The fourth to sixth reference inventions having a configuration that can be preferably employed when implementing the third reference invention will be described later.

In the rolling bearing unit according to the seventh reference invention, the pitch circle diameters of the pockets and the pitch circle diameters of the rolling elements are different from each other.
Furthermore, in the rolling bearing unit according to the first aspect of the present invention, a virtual plane orthogonal to the central axis of the cage based on a gap existing between the inner surface of each pocket and each rolling element. present for, by two ways for each respective rolling bodies, among the degrees of freedom that exist only the number of twice the number of total rolling elements, the gap relating to the degree of freedom of 3 types for each of the retainer, the free remaining By making it smaller than the clearance related to the degree, the displacement in the radial direction of the cage is limited (substantially blocked). Further, a revolution speed detection sensor for measuring the rotation speed of the cage that matches the revolution speed of each rolling element is provided, and the detection signal of the revolution speed detection sensor is equivalent to the outer ring equivalent member and the inner ring equivalent. It is used to determine the load applied between the members.

  According to the rolling bearing unit according to each of the first and third reference inventions, the rotational speed of each rolling element based on the revolution speed detection encoder installed in the cage can be suppressed to a small extent in the radial direction of the cage. As a result, the load applied between the outer ring equivalent member and the inner ring equivalent member, which is calculated based on the revolution speed, can be accurately obtained. Hereinafter, the reason why the measurement accuracy of the revolution speed can be secured from the aspect of obtaining the load under the conditions adopted by the first and third reference inventions will be described.

  As is clear from FIG. 18 described above, when a lateral load is applied between the outer ring equivalent member and the inner ring equivalent member, the revolution speed of the rolling elements arranged between the outer ring equivalent member and the inner ring equivalent member is reliably changed. To do. However, the amount of change in the revolution speed is only about 2 to 3% in consideration of the amount of lateral load that can act on the wheel bearing rolling bearing unit. Although the vertical load is less important than the lateral load in terms of ensuring the vehicle's running stability, the degree of change in the vertical load is almost the same, although not shown. . Therefore, in order to obtain the load acting between the outer ring equivalent member and the inner ring equivalent member with the accuracy required for ensuring the running stability of the vehicle, the revolution speed of each rolling element is determined. It is necessary to detect with high accuracy. Specifically, it is necessary to detect this revolution speed with an accuracy of about ± 0.1%.

  In order to detect this revolution speed with such high accuracy, it is important to increase the pitch precision of the revolution speed detection encoder, and of course, the swing of the cage in which this revolution speed detection encoder is installed. It is also important to suppress exercise. That is, as described with reference to FIGS. 20 to 21 described above, when the center of the pitch circle of each rolling element deviates from the rotation center of the cage, and the revolving speed detection encoder swings, The detection accuracy of the revolution speed of each rolling element is deteriorated. The order of the swinging motion has a revolving primary component, but there is a lower-order swinging motion. For example, there may be a case where the swinging motion of revolution 0.2 to 0.5, specifically about 0.35, becomes a problem, and the order of the swinging motion which is a problem is not stable. There are many cases.

  If the order of the whirling motion is stable like the revolution primary component, it can be dealt with by data processing with a notch filter or adaptive filter, but with regard to detection error based on whirling motion whose order is not stable Such data processing cannot be supported. In this case, it is important to cope with data processing by a low-pass filter or the like that can widen the cutoff frequency range, or to suppress the whirling motion itself. An error component in the vicinity of the revolution 0.35 order can be attenuated by about 10 dB (about 1 / 3.2) by the low-pass filter. Of course, the attenuation value of 10 dB differs depending on the characteristics of the low-pass filter used, or the difference between the analog filter and the digital filter, but since the frequency band to be removed is a low frequency around the revolution 0.35th order, The value of the attenuation of 10 dB (about 1 / 3.2) is the best value (maximum value) that can be expected to be attenuated by using the low-pass filter. Therefore, as described above, in order to detect the revolution speed with an accuracy of about ± 0.1%, the low-pass filter can be used even if the attenuation amount 10 dB (about 1 / 3.2) by the low-pass filter is taken into consideration. The detection accuracy of the revolution speed before data processing must be suppressed to ± 0.32% or less (better than ± 0.32%).

In this way, in order to suppress the detection accuracy of the revolution speed before data processing by the low-pass filter to ± 0.32% or less, assuming that the order of the swing motion is 0.35 order of revolution, the following equation (2) is obtained. As shown, both amplitudes of the whirling motion need to be about 1% or less of the pitch circle diameter of the encoder.
A / PCD = ε / n = 0.0032 / 0.35≈0.0091≈1% (2)
In this equation (2), A is the amplitude of the swing motion, PCD is the pitch circle diameter of the revolution speed detection encoder, and ε is the required revolution speed detection accuracy (0.32% = 0.002). And n represents the order of the whirling motion.

  That is, as apparent from the above equation (2), in order to improve the detection accuracy of the revolution speed before the data processing, both amplitudes A of the swing motion are set to the pitch circle diameter of the revolution speed detection encoder. It is effective to keep it small in relation to PCD. Specifically, in order to suppress the detection accuracy to ± 0.32% or less, both the amplitudes A need to be about 1% or less of the pitch circle diameter PCD. In order to suppress both amplitudes A to about 1% or less of the pitch circle diameter PCD, the radial direction of the cage exists between the rolling surface of each rolling element and the inner surface of each pocket of the cage. It is effective to reduce the pocket clearance value. Both amplitudes of the swinging motion do not increase beyond this pocket gap. Therefore, if this pocket gap is set to 1% or less of the pitch circle diameter PCD, the detection accuracy of the revolution speed before the low-pass filter process is suppressed to ± 0.32% or less, and the revolution speed after the low-pass filter process is detected. The accuracy can be ± 0.1% or less. Based on this revolution speed, the load applied between the outer ring equivalent member and the inner ring equivalent member can be obtained with high accuracy. Such an effect can be obtained by using the axially opposed type revolution speed detecting encoder 25 having a detected surface on one side in the axial direction as shown in FIG. Even the radial opposed type revolution speed detecting encoder 25 used as the detection surface can be obtained similarly {the above equation (2) holds. }.

  The rolling bearing unit according to each of the first and third reference inventions as described above has a large moment in the direction in which the central axes of these two members are displaced from each other by the load applied between the outer ring equivalent member and the inner ring equivalent member. This is effective when no twisting moment is applied. On the other hand, in the case of a rolling bearing unit used in a situation where a large twisting moment is applied between the two members, there is a possibility that sufficient practical performance may not be obtained. That is, when a large twisting moment acts, the arrangement of the rolling elements existing between the two members is disturbed. Specifically, the center points of the rolling elements in the same row do not exist on the same plane. In this state, with respect to all the rolling elements, if the pocket clearance between the respective rolling surfaces and the inner surface of the pocket is small, the rolling surface of any of the rolling elements is the pocket that holds the rolling element. It is strongly pressed against the inner surface. As a result, the rolling element may not be able to rotate normally or the cage may be damaged.

In such a case, it is effective to suppress the swinging motion of the cage by the structure of the present invention . In the case of the rolling bearing unit according to the present invention, since the gaps related to arbitrary three degrees of freedom related to directions that are not parallel to each other are reduced, the displacement in the radial direction of the cage is related to these three kinds of degrees of freedom. Can be reduced to fit the gap. That is, from the aspect of suppressing the displacement in the surface direction, by setting only the gaps related to the three degrees of freedom that are necessary and sufficient in terms of mechanism, it is intended to deform the cage from the rolling element to the cage. The cage is displaced in the radial direction while preventing a large load from being applied, in other words, the whirling motion of the cage moving randomly within a large gap can be suppressed.
Further, in the present invention , since the gap is reduced in the pocket portion having a small dimension (for example, an inner diameter of about 10 mm), the dimensional change due to thermal expansion (shrinkage) becomes a problem as in the conventional example shown in FIG. Hard to become.

  That is, when considering the degree of freedom of the cage 24 on a virtual plane orthogonal to the central axis of the cage 24, as shown in FIG. 3, the degree of freedom Rx in the rotational direction and the degree of freedom in any direction. Three degrees of freedom are conceivable: y and the degree of freedom z perpendicular to this direction. Considering mechanistically, in order to restrict these three degrees of freedom Rx, y, z regarding the cage 24 on the virtual plane, the three degrees of freedom are limited on the virtual plane. It will be good. Accordingly, there are three ways selected appropriately from among the degrees of freedom that exist in the radial direction and the circumferential direction for each rolling element on the virtual plane, and twice the number of these rolling elements in the entire rolling bearing unit. If the degree of freedom is limited, the displacement of the cage 24 on the virtual plane is limited, and the whirling motion of the cage 24 can be suppressed to an extent that does not cause a problem in practice.

In the present invention , it is important to limit the three degrees of freedom appropriately selected from the degrees of freedom existing twice as many as the number of rolling elements as described above. When the number of degrees of freedom to be limited is less than three, the above-mentioned whirling movement cannot be suppressed. On the other hand, when the number is more than three, the whirling motion can be suppressed, but the damage prevention effect of the cage 24 is impaired. In other words, when there are four or more restricted degrees of freedom, even if there is a slight dimensional error or the revolution speed of each rolling element related to these four or more degrees of freedom is slightly different, Strongly presses the inner surface of the pocket, and there is a possibility that a large stress is generated inside the retainer 24 so as to cause damage to the retainer 24. If the number of degrees of freedom to be limited is three, such a problem will not occur.

When the degree of freedom in the circumferential direction is limited with respect to two or more degrees of freedom among the above three kinds of degrees of freedom, the surface of the rolling element and the pocket due to the difference in the revolution speed of the rolling element in the part. It can be considered that the inner surface of each other is pressed against each other. In such a case, the cage 24 is displaced in the radial direction to prevent an excessive stress from being generated in the cage 24. However, the radial displacement at this time is very small. , Almost negligible. As in the present invention , since the revolution speed of the cage 24 needs to be measured with high accuracy, even if this radial displacement cannot be ignored, this whirling becomes a stable and regular motion. In addition, if a signal representing the revolution speed is appropriately calculated by an adaptive filter, a notch filter, or the like, the low-frequency fluctuation as shown by the chain line α in FIG. 21 with respect to the detection signal of the revolution speed detection sensor. Can be corrected.

In the case of the present invention, with respect to some (2 to 3) pockets, only the gap between the inner surface of the pocket and the surface of the rolling element is made small. As a result, the lubrication performance is not impaired. In addition, with respect to the above-mentioned part of the pockets, the necessary lubrication performance can be obtained by securing a clearance in the axial direction of the cage. Therefore, as described above, necessary and sufficient practical performance can be obtained even in the case of a rolling bearing unit used in a situation where a large twisting moment is applied.

When implementing the first reference invention, it is preferable to set both amplitude values to 0.3% or less of the pitch circle diameter of the revolution speed detecting encoder as in the second reference invention. Further, when implementing the third reference invention, preferably, the pocket clearance value is set to 0.3% or less of the pitch circle diameter of the revolution speed detecting encoder as in the fourth reference invention.
In this way, it is possible to prevent the deterioration of the responsiveness associated with the use of the low-pass filter and to obtain the revolution speed of each rolling element with the required accuracy. This point will be described below.

  When the detection signal of the revolution speed detection sensor is processed using a low-pass filter and the error included in the detection signal based on the swinging motion of the cage is suppressed, the revolution speed is obtained based on the detection signal, and The responsiveness of the process of calculating the load applied between the outer ring equivalent member and the inner ring equivalent member is deteriorated. Therefore, the object for which the above error can be suppressed by using the low-pass filter is limited to the case where it is difficult to cause a problem even if there is a slight response delay. For example, in the case of a rolling bearing unit for supporting the wheels of an automobile, the road surface grip force by the wheels (tires) supported by the rolling bearing unit is detected while the automobile is traveling on a gentle curve. Is the case. Also, when detecting a load acting on a rolling bearing unit incorporated in an industrial machine, it is effective because a response delay is unlikely to be a problem.

  On the other hand, for example, when the road grip force is obtained at the moment when the vehicle suddenly changes lane during high-speed traveling, excellent responsiveness is required. Specifically, it is not possible to attenuate a low frequency band such as the vicinity of the above described revolution 0.35 order using a low-pass filter. In such a case, without using a low-pass filter, the vibration of the detection signal of the revolution speed detection sensor in this low frequency band should be attenuated and the revolution speed detection accuracy must be ± 0.1% or less. Don't be.

Assuming that the detection accuracy of the revolution speed is ± 0.1% or less and the swing order is 0.35 order of revolution, as shown in the following equation (3), both amplitudes of the swing motion are about 0 of the encoder PCD. It should be 3% or less. The meaning of the symbols in the expression (3) is the same as that in the expression (2) described above.
A / PCD = ε / n = 0.001 / 0.35≈0.0029≈0.3%
---- (3)
As a method for suppressing both amplitudes of the swing motion to about 0.3% or less of the pitch circle diameter of the revolution speed detecting encoder, it is effective to reduce the pocket clearance. As described above, since both amplitudes of the swinging motion do not increase beyond the pocket gap, if this pocket gap is set to 0.3% or less of the pitch circle diameter of the revolution speed detection encoder, the above-mentioned As apparent from the equation (3), the detection accuracy of the revolution speed can be suppressed to ± 0.1% or less. And based on this revolution speed, the load which acts between an outer ring equivalent member and an inner ring equivalent member is calculated | required with sufficient precision.

  However, if the pocket clearances are too small, grease will not easily enter between the rolling surfaces of the rolling elements and the inner surfaces of the pockets (grease lubrication will be hindered), which will increase the rolling fatigue life of the rolling bearing unit. It is not preferable because it causes a decrease. From experience, if the pocket gap is 50 μm or less, the risk of problems due to deterioration of lubricity increases. Therefore, as in the sixth reference invention, the pocket gap is preferably 50 μm or more. Furthermore, if the pocket clearance is about 100 μm, the problem due to the deterioration of the lubricity hardly occurs regardless of the diameter of the rolling element. On the other hand, in order to obtain the revolution speed of each rolling element with high accuracy, it is preferable to keep the pocket gap as small as possible without causing a problem due to deterioration in lubricity. Therefore, even when the value corresponding to 0.3% of the pitch circle diameter of the revolution speed detecting encoder exceeds 100 μm, the pocket gap can be set to about 100 μm. That is, if the pocket clearance is set to 100 μm or less (50 μm or more) as in the fifth reference invention, the outer ring is based on the detection accuracy of the revolution speed and further based on this revolution speed without reducing the life of the rolling bearing unit. The measurement accuracy of the load acting between the equivalent member and the inner ring equivalent member can be ensured.

Further, when implementing the first and third reference inventions, preferably, the pitch circle diameter of each pocket is made different from the pitch circle diameter of each rolling element as in the seventh reference invention . In this case, it is possible to appropriately select which of the pitch circle diameter of each pocket and the pitch circle diameter of each rolling element is increased. In any case, the value of the pocket clearance in the radial direction of the cage existing between the rolling surface of each rolling element and the inner surface of each pocket can be reduced. In addition, a gap other than the radial gap, which exists between the rolling surface of each rolling element and the inner surface of each pocket, is increased, and the rolling surface of each rolling element and the inner surface of each pocket are increased. The lubricant can be easily taken in between. The seventh reference invention can also be applied to a structure in which the revolving speed detection encoder is not attached to the cage. In this case, it is possible to prevent the cage noise from being generated by suppressing the radial swing of the cage.

For example, FIGS. 10 to 11 show a structure according to the seventh reference invention . In the case of the structure shown in FIGS. 10 to 11, the diameter of the pitch circle P _{28 of} each pocket 28, ₂₈ provided in the cage 24 (the circle connecting the centers of the curvature radii of each pocket 28, 28) is disposed between the pitch circle P ₉ {these rolling elements 9, 9 outer ring raceway 7 and the inner ring raceway 8 of the rolling elements 9, 9 retained in these in each pocket 28, 28 (see FIG. 16, 19) In this state, the diameter of the circles connecting the centers of the rolling elements 9 and 9 is made smaller (the pitch circle P ₂₈ of the pockets 28 and ₂₈ is equal to the pitch circle P ₉ of the rolling elements 9 and ₉ . It is arranged on the inner diameter side).

Structure described in FIG. 10-11, such as, by placing the pitch circle P ₂₈ of each pocket 28, 28 on the inner diameter side of the pitch circle P ₉ of the rolling elements 9 and 9, both of these pitch circle P _28, as compared with the case where to match the P _9, the rolling elements 9, 9 above within each pocket 28, 28 is an amount which can move in the circumferential direction to reduce the circumferential clearance S. Further, the points where the rolling elements 9 and 9 come into contact with the inner surfaces of the pockets 28 and 28 are arranged on the outer diameter side of the pitch circle P _{28 of the} pockets 28 and ₂₈ (in the illustrated example, the cage With respect to the radial direction of 24, these pockets 28, 28 are positioned at the outer diameter side end portions).

That is, in the case of the structure of this reference example, the rolling elements 9, 9 are offset in the pockets 28, 28 to the outside in the radial direction of the retainer 24. It is smaller than the difference between the diameter D of the rolling elements 9 and 9 and the inner diameter R of each of the pockets 28 and 28 (S <RD). In addition, the points where the surfaces (rolling surfaces) of the rolling elements 9 and 9 and the inner surfaces of the pockets 28 and 28 come into contact with the offset are the end portions on the outer diameter side of the pockets 28 and 28. Is located. The size of the gap S is 0.2 to 0.4 mm (S / 2 = 0.1) in the case of a rolling bearing unit for supporting the wheels of a general passenger car, for example, as shown in FIGS. ˜0.2 mm) is preferable.

  The circumferential clearance S of this degree is generated when a moment is applied to the rolling bearing unit and all the rolling elements 9, 9 are not aligned on one plane, and the revolution speeds of the respective rolling elements 9, 9 are generated. In order to absorb the difference (the advance / delay of each of the rolling elements 9, 9 with respect to the rotation of the cage 24). That is, when the rolling bearing unit is used to support the wheel of an automobile on a suspension device, the stationary wheel (outer ring 1) and the rotating wheel (hub 2) are caused by a large moment applied to the rolling bearing unit when the automobile turns. Misalignment (misalignment between central axes) occurs between the two. Based on this misalignment, the contact angles between the rolling elements 9 and 9 and the raceway surfaces (the outer ring raceway 7 and the inner ring raceway 8) become non-uniform for each of the rolling elements 9 and 9, and A difference occurs in the revolution speed of the moving bodies 9 and 9, and the advance and delay of the respective rolling bodies 9 and 9 occur.

The difference in the distance on the circumference of the advance / delay varies depending on conditions such as the magnitude of the moment, but in the case of the rolling bearing unit for supporting the wheel of the automobile, the maximum is about 0.2 mm. Become. Therefore, as described above, if the gap S is 0.2 mm or more, the rolling elements 9 and 9 strongly press the column portion of the cage 24 due to the advance / delay of the rolling elements 9 and 9. This prevents the rolling elements 9 and 9 from applying excessive stress to the cage 24. The increase in the circumferential clearance S is linked to a whirling motion in which the cage 24 is displaced in the radial direction, so the clearance S is suppressed to 0.4 mm or less. On the other hand, the axial gap, which is the amount by which each rolling element 9, 9 can move in the axial direction (left-right direction in FIG. 10, front-back direction in FIG. 11) in each pocket 28, 28, It does not lead to a turning movement. Accordingly, the axial gap is appropriately increased by devising the shape of the inner surface of each of the pockets 28, 28, and the inner surface of each of the pockets 28, 28 and the outer surface (rolling surface) of each of the rolling elements 9, 9. Make it easy to take in grease.

FIG. 12 shows a structure according to a seventh reference example . In the case of the structure shown in FIG. 12, the diameter of the pitch circle P ₂₈ ′ of each pocket 28 provided in the cage 24 is set to the pitch circle P ₉ ′ of each rolling element 9 held in each pocket 28. (The pitch circle P ₂₈ ′ of each pocket 28 is arranged on the outer diameter side of the pitch circle P ₉ ′ of each rolling element 9). The points where the rolling elements 9 and the inner surfaces of the pockets 28 are in contact with the inner diameter side of the pitch circles P ₂₈ ′ of the pockets 28 (in the illustrated example, with respect to the radial direction of the cage 24). These pockets 28 are positioned at the inner diameter side end portions). Even in such a structure, the whirling movement of the cage 24 can be suppressed while making it easy to take in grease between the inner surfaces of the pockets 28 and the outer surfaces of the rolling elements 9.

  In addition, the structure shown in FIG. 12 can also suppress the whirling motion in the radial direction of the cage 24 in the same manner as the structure shown in FIGS. However, in terms of more effectively suppressing the whirling movement, as shown in FIGS. 10 to 11, the points where the rolling elements 9, 9 and the inner surfaces of the pockets 28, 28 abut each other. The structure located in the outer diameter side edge part of the pockets 28 and 28 is preferable. This is because the shape of the portion of the rolling surface of each of the rolling elements 9, 9 that engages with the portion farthest from the rotation axis (so-called equator portion) is retained on the outer diameter side (point A in FIG. 10). In contrast to the cylindrical surface parallel to the central axis of the vessel 24, the inner diameter side (point B in FIG. 10) is an inclined surface inclined with respect to this central axis (to prevent interference with the outer peripheral surface of the hub). Because of that. In order to accurately define the amount of movement of the retainer 24, in order to bring the rolling elements 9 and 9 closer to the equator portion, the point A which is a simple cylindrical surface is the point B which is an inclined surface. It is easier than doing it in parts.

Next, six examples of preferred embodiments for carrying out the present invention will be described with reference to FIGS. 4 to 9 are schematic diagrams for showing the degree of freedom of the engaging portion between the rolling element and the pocket of the cage, which affects the direction and size of the degree of freedom of the engaging portion. The size of the gap between the inner surface of the pocket and the surface of the rolling element is represented by a perfect circle and an ellipse. Of these, the perfect circle has substantially no degree of freedom of the engaging portion between the rolling element and the pocket of the cage (the rolling element is held in the pocket while being constrained in the radial direction and the circumferential direction). Status). On the other hand, an ellipse indicates that there is substantially no degree of freedom in the width direction, but there is a degree of freedom in the length direction. That is, an ellipse that is long in the circumferential direction represents that the rolling element is constrained only in the radial direction in the pocket and held in a state in which the circumferential displacement is allowed. The ellipses that are long in the radial direction indicate that the rolling elements are constrained only in the circumferential direction in the pocket and are held in a state in which the radial displacement is allowed. The retainers shown in FIGS. 4 to 9 are merely for schematically illustrating the present invention, and do not represent the type of the retainer used in carrying out the present invention . In carrying out the present invention , various types of cages conventionally known for holding the rolling elements such as a crown type and a machined die can be used.

First, FIG. 4 shows the invention according to claim 2 as a first example of a preferred embodiment. In the case of this example, the gap regarding the degree of freedom in the radial direction and the degree of freedom in the circumferential portion shown in the upper part of FIG. 4 and the other degree of freedom shown in the lower part of FIG. The gap related to the degree of freedom in the circumferential direction of the rolling elements and the pockets 28 in one set is made smaller than the gap related to the degree of freedom of other parts not shown. For this purpose, for example, the size of the two pockets 28, 28 is restricted in relation to the outer diameter of the rolling elements held in these pockets, and the pocket clearance in the direction of limiting the degree of freedom is reduced. . Since the structure for reducing the pocket clearance has been widely known in the field of rolling bearings, a detailed description thereof will be omitted.

In the case of this example, the degree of freedom y and z in the parallel movement direction described above with reference to FIG. 3 is limited by the set of rolling elements and pockets 28 shown in the upper part of FIG. Further, this portion and another set of rolling elements and pockets 28 shown in the lower part of FIG. 4 limit the degree of freedom Rx in the rotational direction described in FIG. As a result, the cage 24 is not displaced to a practical extent along a virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.
In addition, regarding the rolling elements and pockets 28 in another set shown in the lower part of FIG. 4, if the degree of freedom in the circumferential direction is limited even if the degree of freedom in the radial direction is limited, the rotation The function of limiting the degree of freedom Rx is reduced.

Next, FIG. 5 shows the invention according to claim 3 as a second example of a preferred embodiment. In the case of this example, the gap regarding the degree of freedom in the radial direction and the degree of freedom in the circumferential direction shown in the upper part of FIG. 5 and the other shown in the right part of FIG. The gap relating to the degree of freedom in the radial direction of the rolling element and the pocket 28 in one set is made smaller than the gap relating to the degree of freedom of other parts not shown.
In the case of this example, the degree of freedom y and z in the translation direction described above with reference to FIG. 3 is limited by the pair of rolling elements and pockets 28 shown in the upper part of FIG. Further, this portion and the other set of rolling elements and pockets 28 shown in the right part of FIG. 5 limit the degree of freedom Rx in the rotational direction described in FIG. As a result, the cage 24 is not displaced to a practical extent along a virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.
In addition, regarding the rolling elements and pockets 28 in another set shown in the right part of FIG. 5, if the degree of freedom in the radial direction is limited even if the degree of freedom in the circumferential direction is limited, The function of limiting the degree of freedom Rx in the rotation direction is reduced.

Next, FIG. 6 shows the invention according to claim 4 as a third example of a preferred embodiment. In the case of this example, the gaps related to the radial degrees of freedom in the three sets of rolling elements and pockets 28 and 28 existing at substantially equal intervals in the circumferential direction are defined as the circumferential degrees of freedom of these parts and It is made smaller than the clearance regarding the freedom degree of the other part which abbreviate | omitted illustration.
In the case of this example, the three sets of rolling elements and pockets 28 and 28 limit the degrees of freedom y and z in the translation direction described with reference to FIG. As a result, the cage 24 is not displaced in the radial direction to the extent that it becomes a practical problem with respect to the virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.

  In the case of this example, the degree of freedom Rx in the rotational direction described with reference to FIG. Therefore, it is unsuitable for measuring the revolution speed of each rolling element 9a, 9b based on the rotational speed of the cage as applied to the structure shown in FIGS. However, even in the structure of this example, it can be sufficiently applied to a general rolling bearing unit to suppress noise and vibration based on the whirling motion of the cage. Also, if the position of each rolling element 9a, 9b is displaced in the radial direction, or if there is an error between the pitch circle diameter of the pockets 28, 28 of the cage and the pitch circle diameter of the rolling element, the holding However, since these radial deviations and dimensional errors are smaller than the difference in the revolution speed of each rolling element, it is unlikely to cause a problem.

Next, FIG. 7 shows the invention according to claim 5 as a fourth example of the preferred embodiment. In the case of this example, the gaps related to the degrees of freedom in the circumferential direction of the three sets of rolling elements and the pockets 28 and 28 existing at substantially equal intervals in the circumferential direction are defined as the degrees of freedom in the radial direction of these parts and It is made smaller than the clearance regarding the freedom degree of the other part which abbreviate | omitted illustration.
In the case of this example, the three rolling elements and the pockets 28 and 28 work together so that the degrees of freedom y and z in the translational direction and the degree of freedom in the rotational direction described above with reference to FIG. Limit Rx. As a result, the cage 24 is not displaced to a practical extent along a virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.

Next, FIG. 8 shows the invention according to claim 6 as a fifth example of the preferred embodiment. In the case of this example, circles in two sets of pockets 28 and 28 existing on the left and right in the lower part of FIG. 8 among the three sets of rolling elements and pockets 28 and 28 existing at substantially equal positions in the circumferential direction. The clearance regarding the degree of freedom in the circumferential direction is made smaller than the clearance regarding the degree of freedom in the radial direction of each part and the degrees of freedom of other parts not shown. Further, among the above three sets, the clearance in the radial direction of the remaining one pair of pockets 28 and 28 existing in the upper part of FIG. It is smaller than the gap regarding the degree of freedom of the part.
Also in this example, the three sets of rolling elements and the pockets 28 and 28 work together, so that the degrees of freedom y and z in the parallel movement direction and the freedom in the rotation direction described above with reference to FIG. Limit degree Rx. As a result, the cage 24 is not displaced to a practical extent along a virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.

Further, FIG. 9 shows an invention according to claim 7 as a sixth example of a preferred embodiment. In the case of this example, out of the three sets of rolling elements and pockets 28 and 28 existing at substantially equal intervals in the circumferential direction, the diameters of the two sets of pockets 28 and 28 existing on the left and right in the lower part of FIG. The clearance regarding the degree of freedom in the direction is made smaller than the clearance regarding the degree of freedom in the circumferential direction of these portions and the freedom of the other portions not shown. In addition, among the above three sets, the clearance related to the degree of freedom in the circumferential direction at the remaining one set of pockets 28 in the upper part of FIG. It is smaller than the gap regarding the degree of freedom.
Also in this example, the three sets of rolling elements and the pockets 28 and 28 work together, so that the degrees of freedom y and z in the parallel movement direction and the freedom in the rotation direction described above with reference to FIG. Limit degree Rx. As a result, the cage 24 is not displaced to a practical extent along a virtual plane orthogonal to the central axis, and the cage 24 can be prevented from swinging.

Note that, in any of the structures shown in FIGS. 4 to 9, the gaps related to the three degrees of freedom that are smaller than the gaps related to the degrees of freedom of other portions are set to 100 μm or less as in the invention according to claim 8. It is preferable to suppress. If this gap is too large, the effect of the present invention cannot be exhibited. On the other hand, if this gap is too small, there is a possibility that normal rolling motion of the rolling elements may be hindered and grease lubrication may be insufficient. This point is the same as in the case of the first to seventh reference inventions described above, but in the case of the present invention , since the gaps other than the above three degrees of freedom can be increased, the three degrees of freedom are related. The gap can be made smaller than in the case of the first to seventh reference inventions. Taking these into consideration, the gap with respect to the three degrees of freedom to be reduced is optimally about 10 μm to several tens of μm. However, considering the dimensional error of the cage pocket shape, it is preferable to design the gap to be about 100 μm or less. On the other hand, the gap regarding the remaining degree of freedom is set to several hundred μm or more, for example, about 400 to 600 μm. These values are, for example, values for a ball bearing unit used for supporting a wheel for a passenger car, in which each rolling element has a pitch circle diameter of about 40 to 80 mm and each rolling element has a diameter of about 8 to 13 mm. These values vary substantially in proportion to the pitch circle diameter of each rolling element and the diameter of each rolling element.

  Further, the pocket positions for reducing the gap are illustrated at intervals of 180 degrees in FIG. 4, at intervals of 90 degrees in FIG. 5, and at intervals of 120 degrees in FIGS. 6 to 9, but are not limited to the illustrated angular intervals. However, the number of rolling elements may be determined so that the illustrated angular interval can be set. For example, if the number of rolling elements is set to an integer multiple of 2 in the embodiment of FIG. 4, an integer multiple of 4 in the embodiment of FIG. 5, and an integer multiple of 3 in the embodiments of FIGS. The pockets with the angular intervals can be selected.

4 to 9, when the present invention is carried out, the number of the rolling elements 9, 9 and the pockets 28, 28 of the cage 24 are preferably set as described in claim 9. Are each an integral multiple of 3. The reason for this is as follows.
For example, in the behavior on the two-dimensional plane (in-plane behavior) as shown in FIG. 6 described above, the three-degree-of-freedom constraint is an ideal constraint that is not mechanically excessive or insufficient. The unstable behavior of the vessel 24 is suppressed. However, for example, in the case of the structure shown in FIG. 6, only the three pockets 28 and 28 dominate the behavior of the retainer 24. Therefore, while the retainer 24 makes one revolution (revolution), Based on the undulations of the outer ring raceway 7 and the inner ring raceway 8 (see FIGS. 16 and 19), a swinging behavior of three cycles occurs, resulting in a revolution speed detection error. In this case, if the behavior of the cage 24 is a stable swinging movement as indicated by a broken line b in FIG. 13, error correction using a notch filter or an adaptive filter is possible. On the other hand, when the intervals (pitch) in the circumferential direction of the three pockets 28, 28 with the gaps made small are unequal, the whirling behavior becomes complicated, as shown by the solid line a in FIG. In addition, the waveform is distorted. In such a case, there is a possibility that the error cannot be sufficiently corrected even if a notch filter or an adaptive filter is used.

For example, when the number of the rolling elements 9 and 9 and the pockets 28 and 28 is 10, the basic pitch of each of the pockets 28 and 28 is 36 degrees. Deflection motion generated based on the undulations of the outer ring raceway 7 and the inner ring raceway 8 as described above, with unequal pitches of degrees (3 pitches), 108 degrees (3 pitches), and 144 degrees (4 pitches). It becomes difficult to correct the error. On the other hand, as described in claim 9, the number of the rolling elements 9, 9 and the number of the pockets 28, 28 of the cage 24 are each an integral multiple of 3 to reduce the gap. If the three pockets 28 and 28 are arranged at equal intervals (equal pitch) in the circumferential direction, the main component of the behavior of the cage 24 is only the revolving tertiary component. For this reason, the error correction by the notch filter or the adaptive filter can be appropriately performed, and the revolution speed can be detected with high accuracy.

Incidentally, the rolling element used when the present invention is carried out may be a ball as in the invention according to claim 10 or a tapered roller as described in claim 11 .
Regardless of the type of rolling element, noise and vibration can be suppressed by suppressing the swinging motion of the cage.

Further, the present invention is provided between a suspension device of an automobile and a wheel, and is used for rotatably supporting the wheel with respect to the suspension device .
Furthermore, a revolution speed detection sensor for measuring the rotational speed of the cage that matches the revolution speed of each rolling element is provided, and the detection signal of the revolution speed detection sensor is transmitted between the outer ring equivalent member and the inner ring equivalent member. Used to determine the load applied to
For this reason, according to the present invention, the load applied to the wheel can be accurately obtained with a structure that can be manufactured at a low cost as in the prior inventions shown in FIGS.

The present invention can also be implemented in combination with the invention according to Japanese Patent Application No. 2003-329752. The structure of this prior invention is provided in the cage in order to suppress a change in the gap between the detected surface of the revolution speed detection encoder fixed to the cage and the detection surface of the revolution speed detection sensor. Set the clearance in the axial direction of the cage between any three pockets and the rolling elements held in the pocket smaller than the clearance in the same direction for other pockets. is there.

Whereas the present invention defines a gap in the plane direction of a virtual plane orthogonal to the central axis of the cage, the above-described invention restricts the gap in the axial direction. Therefore, the previous invention and the present invention can be carried out simultaneously. However, the pocket that reduces the gap in the plane direction when implementing the present invention and the pocket that reduces the gap in the axial direction when implementing the above invention are not overlapped with respect to the same pocket (the gap in the plane direction is not It is preferable that the pocket to be reduced and the pocket to reduce the gap in the axial direction are all different. The reason for this is to prevent the gap in the surface direction and the gap in the axial direction from becoming narrow in a specific pocket, so that the grease is not significantly taken into the pocket.

Sectional drawing and the side view which show the 1st example of the revolution speed encoder with which a holder | retainer is mounted | worn. Sectional drawing and side view which show the 2nd example. The schematic diagram which looked at the holder | retainer from the axial direction for showing three kinds of freedom of a holder | retainer in order to demonstrate this invention . The schematic diagram which shows the holder | retainer in the state seen from the axial direction in order to demonstrate the 1st example of preferable embodiment regarding this invention . The figure similar to FIG. 4 which shows the 2nd example. The figure similar to FIG. 4 which shows the 3rd example. The figure similar to FIG. 4 which shows the 4th example. The figure similar to FIG. 4 which shows the said 5th example. The figure similar to FIG. 4 which shows the 6th example. Sectional drawing of a holder | retainer for demonstrating the invention which concerns on a 7th reference example . FIG. 11 is an enlarged AA sectional view of FIG. 10. The figure similar to FIG. 11 for demonstrating another example of the invention which concerns on a 7th reference example . The diagram for demonstrating the influence which the number of rolling elements and a pocket has on the displacement of a holder | retainer regarding the invention described in Claim 9 . Sectional drawing which shows the 1st example of the rolling bearing unit for wheel support with a load measuring apparatus conventionally known. Sectional drawing which shows the 2nd example. Sectional drawing which shows the 1st example of the rolling bearing unit for wheel support with a load measuring device which concerns on a prior invention. The schematic diagram for demonstrating the reason which can measure a load with the structure which concerns on this prior invention. The diagram which shows the relationship between a horizontal direction load and the fluctuation | variation of the revolution speed of each row | line | column. Sectional drawing which shows the 2nd example of the rolling bearing unit for wheel support with a load measuring device which concerns on a prior invention. The schematic diagram for demonstrating the reason for the whirling motion of a cage | casing worsening the precision of revolution speed detection. The diagram showing the output signal of a revolution speed detection sensor similarly. The end view which shows the structure considered previously in order to prevent the whirling of the encoder for revolution speed detection irrespective of the whirling motion of a cage | basket. The fragmentary sectional view which shows the structure considered previously in order to prevent the whirling motion of a cage | basket.

DESCRIPTION OF SYMBOLS 1, 1a Outer ring 2, 2a Hub 3, 3a Rotation side flange 4 Hub body 5 Nut 6 Inner ring 7 Outer ring raceway 8 Inner ring raceway 9, 9a, 9b Rolling element 10, 10a Mounting hole 11 Displacement sensor 12 Sensor ring 13, 13a, 13b Rotational speed detection encoder 14, 14a Cover 15, 15a, 15b Rotational speed detection sensor 16 Knuckle 17 Fixed flange 18 Bolt 19 Screw hole 20 Load sensor 21 Sensor unit 22 Tip 23a, 23b Revolution speed detection sensor 24, 24a , 24b Cage 25, 25a, 25b Revolution speed detection encoder 26 Weight 27 Rim part 28 Pocket

Claims (11)

An outer ring equivalent member on the inner circumferential surface having an outer ring raceway of the double row, the inner ring member having an inner ring raceway of the double row outer peripheral surface, provided rollably between these outer ring raceways and both inner ring raceway A plurality of rolling elements and a cage having a plurality of pockets for holding the rolling elements inside each of the rolling elements; Rolling body guides based on the engagement with the surface of the rolling element , provided between the suspension device of the automobile and the wheel, and used for rotatably supporting the wheel with respect to this suspension device in the bearing unit, it exists for an imaginary plane perpendicular to the central axis of the retainer based on the gap existing between the inner surface and the rolling elements of the pockets, by two ways in each of these rolling elements, 2 of the total number of rolling elements Of the degrees of freedom that exist only in a few, gaps related to the degree of freedom in triplicate for each of the cage, by less than the gap for the remaining degrees of freedom, which limits the displacement in the radial direction of the cage A revolution speed detection sensor for measuring the rotational speed of the cage that matches the revolution speed of each rolling element, and the detection signal of the revolution speed detection sensor is sent to the outer ring equivalent member and the inner ring equivalent member. Rolling bearing unit used to calculate the load applied between the two .   One set of rolling elements and pockets in the radial direction and the circumferential degree of freedom, and the other set of rolling elements and pockets in the circumferential direction of freedom are separated into other parts. The rolling bearing unit according to claim 1, wherein the rolling bearing unit is smaller than a gap related to the degree of freedom.   A gap related to the radial freedom and circumferential freedom in one set of rolling elements and pockets, and a gap related to the radial freedom in another set of rolling elements and pockets, The rolling bearing unit according to claim 1, wherein the rolling bearing unit is smaller than a clearance regarding the degree of freedom.   The rolling bearing unit according to claim 1, wherein a gap related to the degree of freedom in the radial direction in the three sets of rolling elements and pockets is smaller than a gap related to the degree of freedom in other parts.   The rolling bearing unit according to claim 1, wherein the clearances related to the degrees of freedom in the circumferential direction at the three sets of rolling elements and pockets are made smaller than the clearances related to the degrees of freedom of the other portions.   The gap related to the radial degree of freedom in one set of rolling elements and pockets, and the gap related to the degree of freedom in the circumferential direction in the other two sets of rolling elements and pockets are larger than the gap related to the degree of freedom in other parts. The rolling bearing unit according to claim 1, which is reduced in size.   The clearance related to the circumferential freedom in one set of rolling elements and pockets and the clearance related to the radial freedom in the other two sets of rolling elements and pockets are larger than the clearance related to the degrees of freedom in other parts. The rolling bearing unit according to claim 1, which is reduced in size.   The rolling bearing unit according to any one of claims 1 to 7, wherein a clearance regarding three degrees of freedom that is smaller than a clearance regarding the remaining degrees of freedom is 100 µm or less.   The rolling bearing unit according to claim 1, wherein the number of rolling elements and the number of pockets of the cage are integer multiples of 3, respectively.   The rolling bearing unit according to claim 1, wherein the rolling element is a ball.   The rolling bearing unit according to claim 1, wherein the rolling element is a tapered roller.

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